I have to agree with the householder's and your definition of evil elbib.
Evil starts as a choice to do something bad. This lives within all of us. If Jesus was a real person, he, too, had this within him.
It was Christianity that decided to personify, externalize, and elevate evil to the status of person-hood by giving it a proper, formal name. By doing this, Christianity has exonerated themselves from the responsibility of evil, ie the choice to do bad. It is where "The Devil Made Me Do It" ideal originated. Just think on that for a bit and what that actually means.
James Mixon said: Satan became an Angel of light for you, go figure.
elbib, WTWizard has some interesting thoughts on the whole Satan - God - Bible thing.